JP2006129278A - Loudspeaker unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a loudspeaker unit capable of constituting a loudspeaker having a low minimum resonance frequency f0 without enlarging a loudspeaker box by a simple constitution and obtaining a high maximum sound pressure. <P>SOLUTION: In the loudspeaker unit 20a, a ring-shaped supporting plate 260 is interposed in a frame 201, and a constitution is adopted supporting a diaphragm 230 by the annular supporting plate 260. Consequently, the inside diameter of the frame 201 is increased without changing the sizes of the diaphragm 230 and the loudspeaker box 10, and the diameter of a damper 250a housed in the frame 201 is enlarged, thus solving the problem. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a speaker unit used for various audio equipment.

  FIG. 4 is a cross-sectional view showing a configuration of a conventional speaker. This speaker has a speaker box 10 and a speaker unit 20 accommodated in the speaker box 10. The configuration of the speaker unit 20 is as follows. First, the frame 201 is a tray-like member for fixing the entire speaker unit 20 to the speaker box 10, the side wall surface is shaped like a staircase, and has an opening at the center of the bottom surface. The frame 201 is accommodated in an opening provided in the baffle plate 11 on the front surface of the speaker box 10, and a peripheral portion is fixed to an edge of the opening. On the back side of the bottom surface of the frame 201, there are an upper plate 211, a permanent magnet 212, and a lower plate 213 that are stacked and fixed. The upper plate 211 is fixed to the bottom side of the frame 201. The permanent magnet 212 and the upper plate 211 have a ring shape. The lower plate 213 has a center pole 213a upright at the center. The center pole 213a sequentially penetrates through the central openings of the permanent magnet 212, the upper plate 211, and the frame 201 and protrudes toward the front of the speaker. Yes.

  The voice coil 220 is a hollow cylindrical member and houses the center pole 213a inside. A winding 220a through which a drive current is passed is provided at the lower part of the voice coil 220, and the winding 220a is located in a magnetic gap between the upper plate 211 and the center pole 213a. The diaphragm 230 is a cone-shaped member having a hole in the center. The inner peripheral edge of the central hole of the diaphragm 230 is fixed to the peripheral part near the top of the voice coil 220, and the outer peripheral edge of the diaphragm 230 is connected to the frame 201 via the edge 240. . The damper 250 is formed by molding a cloth impregnated with a synthetic resin into a concentric corrugated shape, and has a hole in the center thereof. In the damper 250, the inner peripheral edge of the central hole is fixed to the outer peripheral part of the voice coil 220, and the outer peripheral edge is fixed to the frame 201. The damper 250 plays a role of regulating the movement direction of the voice coil 220 in the axial direction. In addition, the shape of the diaphragm 230, the frame 201, and the damper 250 viewed from the front of the speaker is, for example, a circle.

  In such a configuration, when a drive current is applied to the winding 220a of the voice coil 220, the voice coil 220 moves in a piston motion and the diaphragm 230 vibrates in accordance with the change in polarity of the drive current. As a result, an air density wave is generated on the surface of the diaphragm 230, which is transmitted as sound waves to the front of the speaker.

The speaker unit 20 described above can be roughly modeled by a resonance circuit as shown in FIG. In this figure, the inductance m corresponds to the inertia amount of the vibration system such as the diaphragm 230 and the voice coil 220, and the capacitor s is restored to the vibration system by the stiffness, that is, the elasticity of the diaphragm 230 and the damper 250. It corresponds to power. The resistance r corresponds to mechanical resistance such as air friction resistance given to the vibration system. The voltage V corresponds to the driving force generated by energizing the winding 220a. The lowest resonance frequency f0, which is an important factor that determines the output characteristics of the speaker unit 20, is given by the following equation.
f0 = (1 / 2π) √ (s / m) (1)

  When the speaker unit 20 is attached to a sealed speaker box 10 as shown in FIG. 4, the air in the speaker box 10 gives a restoring force to the vibration system. Therefore, the equivalent circuit in FIG. The capacitor corresponding to is connected in series with the capacitor s. For this reason, the minimum resonance frequency f0 of the speaker is higher than that without the speaker box 10.

The lowest resonance frequency f0 is one of important parameters that determine the output characteristics of the speaker. In order to configure a speaker having excellent reproduction capability in a low frequency range, it is necessary to lower this minimum resonance frequency f0. Conventionally, there are the following techniques for reducing the lowest resonance frequency f0 of a speaker. First, the first conventional technique is to lower the minimum resonance frequency f0 by increasing the inertia amount of the vibration system. The second prior art is to lower the lowest resonance frequency f0 by increasing the diameter of the damper and lowering the stiffness. The third prior art is to make the damper soft by changing the material of the damper, the amount of impregnation of the resin, etc., and lower the lowest resonance frequency f0 by lowering the stiffness. The fourth prior art uses a specially shaped damper that is a folded sheet having a large area, and lowers the lowest resonance frequency f0 by lowering the stiffness. The fourth prior art is disclosed in, for example, Patent Document 1.
JP-A-10-94089

  However, if the lowest resonance frequency f0 is lowered by the first conventional technique, the efficiency of converting the drive signal, which is an electrical signal, into vibration of the diaphragm decreases as the inertial amount of the vibration system increases. There is a problem that it is difficult to increase the maximum sound pressure at the resonance frequency f0. Further, if the lowest resonance frequency f0 is lowered by the second prior art, there is a problem that the size of the entire speaker is increased. The reason is as follows. First, in the speaker assembly process, a damper is disposed inside the frame, and then a diaphragm is disposed above the damper inside the frame. For this reason, the diameter of the diaphragm must be the same as or larger than that of the damper. On the other hand, in order to obtain appropriate acoustic characteristics in the speaker, it is necessary to maintain a certain relationship between the diameter of the diaphragm and the volume of the speaker box. Therefore, when the diameter of the damper is increased to lower the minimum resonance frequency f0, the diameter of the diaphragm must be increased accordingly, and the volume of the speaker box must be increased in accordance with the diameter of the diaphragm. is there. Further, when the lowest resonance frequency f0 is lowered by the third prior art, there is a problem that the strength of the damper is insufficient, the vibration of the voice coil becomes unstable and the durability is lowered. If the lowest resonance frequency f0 is to be lowered by the fourth prior art, there is a problem in that the cost increases because the damper is processed into a special shape, and the speaker becomes expensive.

  The present invention has been made in view of the circumstances described above, and constitutes a speaker that has a simple structure and a low minimum resonance frequency f0 and a high maximum sound pressure without increasing the size of the speaker box. An object of the present invention is to provide a speaker unit that can be used.

The present invention includes a frame having an opening, a movable part that is accommodated in the frame and vibrates according to a drive signal, a damper that is accommodated in the frame and restricts the vibration direction of the movable part, and the opening A ring-shaped support plate having an outer peripheral edge fixed to the opening of the frame, and a diaphragm supported by an outer peripheral portion of the movable portion and an inner peripheral edge of the opening of the ring-shaped support plate; A speaker unit is provided.
According to this invention, since the ring-shaped support plate is interposed between the vibration plate and the frame and the vibration plate is fixed to the frame via the ring-shaped support plate, the vibration plate is enlarged. Without increasing the size of the frame, the damper accommodated in the frame can be increased. Therefore, without increasing the speaker box, the damper can be increased, the minimum resonance frequency f0 of the speaker can be lowered, and the maximum sound pressure in the low sound range can be increased.

<First Embodiment>
FIG. 1 is a cross-sectional view showing a configuration of a speaker using the speaker unit 20a according to the first embodiment of the present invention. This speaker is characterized in that the speaker box 10 and the diaphragm 230 shown in FIG. 4 are maintained as they are, and the damper 250 is replaced with a damper 250a having a larger diameter. In order to increase the diameter of such a damper, in the speaker unit 20a according to the present embodiment, the frame 201 is replaced with a frame 201a having a larger diameter, and a ring-shaped support plate 260 is provided at the front opening of the frame 201a. It is fixed. The outer peripheral edge of the diaphragm 230 is connected to the inner peripheral edge of the ring-shaped support plate 260 via the edge 240.

  According to this embodiment, since the ring-shaped support plate 260 is interposed inside the frame 201 and the vibration plate 230 is supported by the ring-shaped support plate 260, the vibration plate 230 and the speaker box are used. The inner diameter of the frame 201 can be increased without changing the size of 10, and the diameter of the damper 250a accommodated in the frame 201 can be increased. Therefore, according to the present embodiment, without increasing the size of the speaker box 10, the diameter of the damper 250a is increased, the stiffness that generates the restoring force of the vibration system, that is, the elastic force is reduced, and the minimum resonance frequency f0 is lowered. This can widen the bass reproduction band. Further, according to the present embodiment, by increasing the diameter of the damper 250a, it is possible to widen the vibration possible range of the voice coil 220 that is the movable part and increase the maximum sound pressure in the low frequency range. In addition, since the possible vibration range of the voice coil can be expanded in this way, the distortion of the reproduced sound waveform when the same drive signal is given can be reduced as compared with a normal speaker.

Second Embodiment
FIG. 2 is a sectional view showing the structure of a speaker unit 20b according to the second embodiment of the present invention. Differences between the speaker unit 20b and the speaker unit 20a in the first embodiment are as follows. First, in the first embodiment, a plate-shaped support plate is used as a ring-shaped support plate that supports the outer peripheral edge of the diaphragm 230. However, in this embodiment, a horn-shaped ring-shaped support plate 260b is used. Yes. In addition, a frame 201b having an expanded opening is used instead of the frame 201a so that the horn-shaped ring-shaped support plate 260b can be accommodated.

  Also in the present embodiment, the diameter of the damper 250a can be increased without increasing the size of the speaker box 10, and the same effect as in the first embodiment can be obtained. Further, according to this embodiment, since the ring-shaped support plate 260b that supports the diaphragm 230 is a horn shape, the ring-shaped support plate 260b functions as a guide for guiding the reproduced sound in the high frequency range to the front of the speaker. The effect that the directivity control of the reproduced sound becomes easy can be obtained.

<Third Embodiment>
FIG. 3 is a sectional view showing the structure of a speaker unit 20c according to the third embodiment of the present invention. In the speaker unit 20a in the first embodiment, one damper 250a is used, but in the present embodiment, two dampers 250a1 and 250a2 are used. More specifically, in this embodiment, ring-shaped dampers 250a1 and 250a2 are stretched inside the ring 250R in a state of being separated from each other, and the ring 250R is formed on a step portion formed on the inner wall of the frame 201a. It is fixed. As in the first embodiment, the inner peripheral edge of the central opening of the dampers 250a1 and 250a2 is fixed to the outer periphery of the voice coil 220.

  In the present embodiment, since the two dampers 250a1 and 250a2 regulate the vibration direction of the voice coil 220, an effect of increasing the vibration stability of the voice coil 220 is obtained. In addition, when two dampers are used in this manner, the stiffness acting on the vibration system is increased. However, in this embodiment, since the diameter of the damper can be increased, two dampers are used in the conventional speaker. Compared to the case of using them in layers, the minimum resonance frequency f0 can be lowered and the maximum sound pressure in the low sound range can be increased.

<Other embodiments>
While several embodiments of the present invention have been described above, the present invention may be implemented in a form in which modifications are made to these. For example, in the above-described embodiments, in the speaker unit, the shapes of the diaphragm, the frame, and the damper viewed from the front of the speaker are circular. However, the constituent members of these speaker units do not have to be circular, and may be oval or oval.

It is sectional drawing which shows the structure of the speaker which is 1st Embodiment of this invention. It is sectional drawing which shows the structure of the speaker which is 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the speaker which is 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the conventional speaker. It is a circuit diagram which shows the structure of the equivalent circuit of the speaker.

Explanation of symbols

  20a, 20b, 20c ... speaker unit, 201a, 201b ... frame, 220 ... voice coil, 250a, 250a1, 250a2 ... damper, 230 ... diaphragm, 260, 260b ... ring-shaped support plate.

Claims (2)

A frame having an opening;
A movable part housed in the frame and vibrating in response to a drive signal;
A damper that is housed in the frame and restricts the vibration direction of the movable part;
A ring-shaped support plate having an opening and an outer peripheral edge fixed to the opening of the frame;
A speaker unit comprising: a diaphragm supported by an outer peripheral portion of the movable portion and an inner peripheral edge portion of an opening of the ring-shaped support plate.   The speaker unit according to claim 1, wherein the ring-shaped support plate has a horn shape.

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